1. Field of the Invention
The present invention relates to a defect detection apparatus for detecting a defect such as a dust, a flaw, a dirt on an object surface from a multi-valued image including shading, acquired by picking up an image of the object surface, a defect detection method employed in the defect detection apparatus, and a computer program for making a computer execute processing in the defect detection method.
2. Description of the Related Art
As a conventional example, an inspection apparatus has been proposed in which n-order approximation is performed by adopting the least square method on each line in an original image which was acquired by image-pickup by a digital camera and includes shading and a singular point formed of a defect such as a dirt, a flaw or a dirt, data acquired on all lines are integrated to generate shading image data as flattened data, a difference between the original data and the shading image data is calculated, and when the difference shows a singular point larger than a prescribed value, the singular point is determined to be a singular point due to the defect (refer to e.g. Japanese Patent Application Laid-Open No. 2006-050356).